Impact of disease free status on prognosis in metastatic non-small round cell soft tissue sarcomas

The aim of this study is to examine the impact of disease free (DF) status on the prognosis in patients with metastatic non-small round cell soft tissue sarcoma (STS). We retrospectively reviewed 51 metastatic STS patients who were treated in Nagoya University Hospital from 2005 to 2015. The relation between various clinical factors and overall survival (OS) was analyzed. The log rank test and Cox's proportional hazards test were used to evaluate the differences between groups. p-values of <0.05 were considered to indicate significance. The median follow-up period after first metastasis was 23.5 (1.6-97.1) months. There were 30 males and 21 females with a median age of 62 (15-88) years at first metastasis. The histologic subtypes were 17 undifferentiated pleomorphic sarcoma, 10 liposarcoma, 8 malignant peripheral nerve sheath tumor, and 16 others. Thirty patients had more than 2 metastases, and 15 patients had primary or local recurrent tumors. The metastatic sites were 31 lung only, 8 bone only, and 12 others. Twenty-two patients achieved DF status after surgeries and in one case proton radiotherapy for bone metastasis. DF status was marginally or significantly associated with good prognosis in patients with both pulmonary (p = 0.055) and extrapulmonary metastasis (p = 0.029). On multivariate analysis, DF status (p = 0.010) was an independent good prognostic factors for OS. In metastatic non-small round cell STS, it is an important treatment concept to achieve DF status whenever possible. This concept can apply both to pulmonary and extrapulmonary metastasis.